diff --git a/src/Microsoft.Agents.A365.DevTools.Cli/Services/Agent365ToolingService.cs b/src/Microsoft.Agents.A365.DevTools.Cli/Services/Agent365ToolingService.cs
index 578b0839..f4f83640 100644
--- a/src/Microsoft.Agents.A365.DevTools.Cli/Services/Agent365ToolingService.cs
+++ b/src/Microsoft.Agents.A365.DevTools.Cli/Services/Agent365ToolingService.cs
@@ -159,6 +159,46 @@ private class ApiStatusResponse
         }
     }
 
+    /// <summary>
+    /// Builds a populated failure <see cref="PublishMcpServerResponse"/> from a failed publish response
+    /// body so the caller surfaces the server's actual error. The publish path previously discarded the
+    /// body and returned <c>null</c>, which the executor rendered as the misleading "No response received"
+    /// no matter what the server reported (a duplicate-instance rejection, a validation error, or a
+    /// downstream 5xx). Handles the platform's { Status, Message } envelope — including double-serialized
+    /// bodies, since the platform returns its already-JSON string via Ok(string) which re-serializes it —
+    /// and ASP.NET { error[, details] } / { message } problem bodies, falling back to the status code when
+    /// the body carries no readable message.
+    /// </summary>
+    /// <param name="responseContent">The raw failure response body.</param>
+    /// <param name="statusCode">The HTTP status code, used only when the body has no readable message.</param>
+    /// <param name="logger">Logger for the double-serialization-aware deserialization helper.</param>
+    /// <returns>A non-null failure response whose <see cref="PublishMcpServerResponse.Message"/> is set.</returns>
+    internal static PublishMcpServerResponse BuildPublishFailureResponse(
+        string? responseContent,
+        System.Net.HttpStatusCode statusCode,
+        ILogger logger)
+    {
+        // Prefer the platform's { Status, Message } envelope (the deserialization helper transparently
+        // unwraps double-serialized bodies).
+        var envelope = JsonDeserializationHelper.DeserializeWithDoubleSerialization<PublishMcpServerResponse>(
+            responseContent ?? string.Empty, logger);
+        var message = envelope?.Message;
+
+        // Otherwise fall back to ASP.NET-style { error[, details] } / { message } problem bodies.
+        if (string.IsNullOrWhiteSpace(message))
+        {
+            message = ExtractErrorMessage(responseContent);
+        }
+
+        return new PublishMcpServerResponse
+        {
+            Status = "Failed",
+            Message = string.IsNullOrWhiteSpace(message)
+                ? $"Server returned {statusCode}"
+                : message,
+        };
+    }
+
     /// <summary>
     /// Common helper method to log HTTP request details
     /// </summary>
@@ -523,7 +563,10 @@ private string BuildProvisionIdentityUrl(string environment, string serverName)
             var (isSuccess, responseContent) = await ValidateResponseAsync(response, "publish MCP server", cancellationToken);
             if (!isSuccess)
             {
-                return null;
+                // Surface the server's actual error instead of returning null (which the executor renders
+                // as the misleading "No response received"). ValidateResponseAsync already flags both
+                // non-2xx responses and 200 bodies carrying a { Status: "Failed" } envelope.
+                return BuildPublishFailureResponse(responseContent, response.StatusCode, _logger);
             }
 
             // Try to deserialize response, but allow for empty/null response
diff --git a/src/Tests/Microsoft.Agents.A365.DevTools.Cli.Tests/Services/Agent365ToolingServicePureFunctionTests.cs b/src/Tests/Microsoft.Agents.A365.DevTools.Cli.Tests/Services/Agent365ToolingServicePureFunctionTests.cs
index 86539da0..d60ebd8f 100644
--- a/src/Tests/Microsoft.Agents.A365.DevTools.Cli.Tests/Services/Agent365ToolingServicePureFunctionTests.cs
+++ b/src/Tests/Microsoft.Agents.A365.DevTools.Cli.Tests/Services/Agent365ToolingServicePureFunctionTests.cs
@@ -3,6 +3,9 @@
 
 using FluentAssertions;
 using Microsoft.Agents.A365.DevTools.Cli.Services;
+using Microsoft.Extensions.Logging.Abstractions;
+using System.Net;
+using System.Text.Json;
 
 namespace Microsoft.Agents.A365.DevTools.Cli.Tests.Services;
 
@@ -87,6 +90,92 @@ public void ExtractErrorMessage_ReturnsNull_WhenJsonHasNoKnownFields()
         Agent365ToolingService.ExtractErrorMessage(json).Should().BeNull();
     }
 
+    // --- BuildPublishFailureResponse tests ---
+
+    [Fact]
+    public void BuildPublishFailureResponse_SurfacesEnvelopeMessage_WhenDoubleSerialized()
+    {
+        // The platform returns its already-JSON string via Ok(string), which serializes it a second
+        // time. This is the exact shape a duplicate-instance rejection reaches the CLI as.
+        const string expected = "MCP server 'msdyn_DataverseMCPServer' is already published in environment 'env' under alias 'DG_DV_S22'. Only one published instance is allowed per server. Unpublish the existing instance before republishing.";
+        var inner = JsonSerializer.Serialize(new { Status = "Failed", Message = expected });
+        var doubleSerialized = JsonSerializer.Serialize(inner);
+
+        var result = Agent365ToolingService.BuildPublishFailureResponse(doubleSerialized, HttpStatusCode.OK, NullLogger.Instance);
+
+        result.Should().NotBeNull();
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be(expected);
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_SurfacesEnvelopeMessage_WhenSingleSerialized()
+    {
+        const string expected = "Custom MCP server 'x' in the environment 'env' is not setup correctly. Please recreate the server and try publishing again.";
+        var body = JsonSerializer.Serialize(new { Status = "Failed", Message = expected });
+
+        var result = Agent365ToolingService.BuildPublishFailureResponse(body, HttpStatusCode.OK, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be(expected);
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_SurfacesError_FromAspNetProblemBody()
+    {
+        var body = """{"error":"DisplayName is required in the request body"}""";
+
+        var result = Agent365ToolingService.BuildPublishFailureResponse(body, HttpStatusCode.BadRequest, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be("DisplayName is required in the request body");
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_PrefersDetails_FromAspNetErrorAndDetailsBody()
+    {
+        var body = """{"error":"Failed to publish (v2) MCP server to Dataverse environment","details":"TEDS API call failed with status 403"}""";
+
+        var result = Agent365ToolingService.BuildPublishFailureResponse(body, HttpStatusCode.InternalServerError, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be("TEDS API call failed with status 403");
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_FallsBackToStatusCode_WhenBodyIsEmpty()
+    {
+        var result = Agent365ToolingService.BuildPublishFailureResponse(string.Empty, HttpStatusCode.BadGateway, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be("Server returned BadGateway");
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_FallsBackToStatusCode_WhenBodyIsNull()
+    {
+        var result = Agent365ToolingService.BuildPublishFailureResponse(null, HttpStatusCode.InternalServerError, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be("Server returned InternalServerError");
+    }
+
+    [Fact]
+    public void BuildPublishFailureResponse_SurfacesRawContent_WhenBodyIsNotJson()
+    {
+        var result = Agent365ToolingService.BuildPublishFailureResponse("Bad Gateway", HttpStatusCode.BadGateway, NullLogger.Instance);
+
+        result.Status.Should().Be("Failed");
+        result.IsSuccess.Should().BeFalse();
+        result.Message.Should().Be("Bad Gateway");
+    }
+
     // --- RedactSecretsFromPayload tests ---
 
     [Fact]